I live in Minnesota. The winters here are as dry as they are cold, and by mid-December I'm slathering myself with lotion on a daily basis just to keep my skin from disintegrating. My question is, am I getting caught in a vicious cycle? I've often heard people casually remark that using lotion, lip balm, etc, eventually results in a compensatory response such that your body stops creating its own natural moisturizers. Is there any truth to this? —Katrina
Spoken like a true Minnesotan, Katrina. Labor Day weekend is upon us, and you know what that means. Winter's here.
The larger issue you raise is whether the products of civilization sap our natural bodily defenses and turn us into helpless lapdogs. Little research has been done on whether moisturizer weakens healthy skin's ability to protect itself. But what there is suggests it might.
Moisturizers and lotions serve three basic purposes: they act as a barrier against irritants, they supplement natural skin moisture, and they help repair irritated or damaged skin. The key components in moisturizers can be variously categorized as humectants, which draw the body's moisture to the skin surface; occlusives, which help prevent water from escaping the skin; emollients, which fill gaps in the skin; proteins and acids to assist the body's natural moisturizing processes; and non-steroidal anti-inflammatory agents, which can help repair dry skin in people suffering from eczema.
Once a moisturizer has been applied and the water in it evaporates, the emulsified lipids left behind—fats, essentially—can penetrate the outer layer of skin and apparently improve its hydration level, as indicated by an increase in the skin's electrical capacitance. Repeated application to healthy skin can increase hydration levels within two days; the effect lasts for a week after stopping.
That's good. But every silver lining must have its dark cloud. One study examined the use of a lipid-rich moisturizer three times a day on the healthy forearm skin of 20 volunteers. After four weeks the applications of moisturizer were stopped, and a patch of sodium lauryl sulfate, a common detergent, was applied to both of each subject's forearms—one treated, the other untreated—to measure the level of irritation on each. Significant differences were seen in water loss through the skin, indicating the moisturized skin was more susceptible to the irritant. That's bad.
Another study examined how moisturizer might affect healthy skin in test subjects with contact allergies. Twenty-two volunteers, 12 of whom were known to be allergic to nickel, applied a lipid-rich moisturizer to their upper arm three times a day for a week. The moisturizer was then stopped and patches containing nickel chloride solution were applied to both treated and untreated skin. The ones with the nickel allergy demonstrated significantly increased sensitivity shortly after application. More bad.
To be clear, none of this necessarily demonstrates that lotions cause your skin to stop moisturizing itself naturally. In the study using using moisturizer followed up with detergent, for example, the researchers theorized that the extra moisture made the skin more permeable and thus more vulnerable to irritants. The fact remains that for healthy skin, the lotion made things worse, not better.
These studies focused on lipid-rich moisturizers. We found another study comparing high-lipid-content and moderate-to-low-lipid-content moisturizer when used on healthy skin. Again, healthy volunteers used the moisturizers three times a day, and then tested their skin reactions to a detergent patch. The skin treated with the high-lipid moisturizer reacted more intensely to the detergent than untreated skin; for lower-lipid moisturizer, there was no measurable difference between the treated and the untreated skin. Conclusion number one: high-lipid moisturizers make skin more vulnerable to irritation. Conclusion number two: neither type of moisturizer increased protection against skin irritants.
Still another study tested nine different moisturizers and found five increased moisture loss in healthy skin—thus actually drying the skin out more—while none of them decreased moisture loss. On the other hand, when these moisturizers were tested on damaged skin, three of them reduced moisture loss and none increased it.
While a lot of this sounds ominous, don't toss your moisturizers yet. The benefits of moisturizer on damaged skin have been demonstrated by numerous studies, and research has found healthy skin can benefit from some moisturizers. Still, it appears we can say two things:
1. There's only limited benefit to applying moisturizer to healthy skin.
2. Some types of moisturizer may make your skin more susceptible to irritation and damage.
Choosing the right moisturizer is more complicated than you might think—for example, some studies have found that different racial skin types show varying sensitivity to different kinds of moisturizers.
U.S. sales of hand and body lotion exceed $775 million annually. High time we knew if it was doing us more harm than good.
Send questions to Cecil via straightdope.com or write him c/o Chicago Reader, 350 N. Orleans, Chicago 60654.